Communication Between Portable Apparatus and Counterpart Apparatus

ABSTRACT

An apparatus is disclosed. The apparatus comprises a communication interface unit configured to receive reference biosignal data, and a wireless interface unit configured to receive a plurality of candidate biosignal transmissions from candidate biosignal transmitters. A comparison unit of the apparatus is configured to compare the reference biosignal data with the candidate biosignal transmissions, thus resulting in comparison data. The wireless interface unit is configured to execute a pairing protocol with a candidate biosignal transmitter of a candidate biosignal transmission by utilizing the comparison data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Ser. No. 12/401,023filed Mar. 10, 2009, which claims priority to Finnish Patent ApplicationNo. 20085280 filed Apr. 3, 2008, which are incorporated herein byreference.

BACKGROUND

1. Field

The invention relates to a counterpart apparatus capable ofcommunicating with a portable apparatus.

2. Description of the Related Art

A portable apparatus, such as a heart rate monitor, may communicateinformation, such as heart activity data, to a counterpart apparatus,such as an exercise apparatus, over a radio link. In order to be able tocommunicate, the radio transceivers of the portable apparatus and thecounterpart apparatus need first to be paired together. This is achievedby executing a pairing protocol. However, as there may be many portableapparatuses present, and possibly also many counterpart apparatuses maybe present, it may be problematic to find out which portable apparatuswishes to be paired together with a specific counterpart apparatus.

SUMMARY

The present invention seeks to provide improvements in the communicationbetween a portable apparatus and a counterpart apparatus.

According to an aspect of the present invention, there is provided anapparatus as specified in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are described below, by way ofexample only, with reference to the accompanying drawings, in which

FIG. 1 illustrates a portable apparatus and a counterpart apparatus;

FIGS. 2, 3 and 4 illustrate various embodiments of a portable apparatusand a counterpart apparatus;

FIG. 5 is a flowchart illustrating an embodiment of a communicationmethod; and

FIGS. 6, 7, 8, 9 and 10 illustrate further embodiments of the portableapparatus and the counterpart apparatus.

DETAILED DESCRIPTION

The following embodiments are exemplary. Although the specification mayrefer to “an”, “one”, or “some” embodiment(s) in several locations, thisdoes not necessarily mean that each such reference is to the sameembodiment(s), or that the feature only applies to a single embodiment.Single features of different embodiments may also be combined to provideother embodiments.

FIG. 1 illustrates a portable apparatus 100 and a counterpart apparatus106. FIG. 1 is a simplified block diagram that only shows some elementsand functional entities, all being logical units whose implementationmay differ from what is shown. The connections shown in FIG. 1 arelogical connections; the actual physical connections may be different.It is apparent to a person skilled in the art that the describedapparatuses 100, 106 may also comprise other functions and structures.It should be appreciated that some functions, structures, and elements,and the protocols used for communication are irrelevant to the actualinvention. Therefore, they need not be discussed in more detail here.The specifications of apparatuses 100, 106 develop rapidly. Suchdevelopment may require extra changes to an embodiment. Therefore, allwords and expressions should be interpreted broadly and they areintended to illustrate, not to restrict, the embodiments. Although theapparatuses 100, 106 have been depicted as separate single entities,different parts may be implemented in one or more physical or logicalentities.

The term ‘portable apparatus’ 100 may refer to a complete device that auser is capable of carrying around, or to a part of such a device. Thecomplete device 100 may be a heart rate monitor, a heart ratetransmitter wearable on the chest of a user, a personal measurementdevice, a wrist-worn measurement device, or a subscriber terminal of aradio system, for example. A part of such a device 100 may be anelectronic circuit implementing the described behavior of the portableapparatus 100 embodiments. The electronic circuit may comprise logiccomponents, standard integrated circuits, and/or application-specificintegrated circuits (ASIC).

The term ‘counterpart apparatus’ 106 may refer to a complete devicecapable of interacting with the portable device 100, or to a part ofsuch a device. In a special case, the counterpart apparatus 106 may evenbe a wrist apparatus. The complete device 106 may be a computer, anexercise apparatus, or a health club apparatus, for example. A part ofsuch a device 106 may be an electronic circuit implementing thedescribed behavior of the counterpart apparatus 106 embodiments. Thecomputer may be a personal computer (such as a desktop computer, alaptop computer, or a palmtop computer). The computer may also be aserver computer. The computer may store and process heart activity dataof countless persons. The computer may be team specific, i.e. it is usedto process the heart activity data of a certain team. Alternatively, thecomputer may provide heart activity data storage and analysis servicesto a wide audience, as a world-wide web (WWW) server over the Internet,for example. If the counterpart apparatus 106 is an exercise apparatus,such as a treadmill, the training load may be regulated, a diary may bestored, etc. utilizing the communication to be described later on.

The portable apparatus 100 comprises two communication devices: aninduction-based transmitter 102 and a radio transceiver 104.Correspondingly, the counterpart apparatus 106 comprises aninduction-based receiver 108 and a radio transceiver 110.

Consequently, two different wireless communication technologies areused: induction-based technology utilizing a magnetic field, and aradio-based technology utilizing electric radiation. It is to be notedthat both technologies involve both the magnetic field and the electricradiation, but the separation is based on the fact that either one ofthese physical phenomena predominates and is only used for thecommunication in each technology.

A crucial difference between these two communication technologies is thesignal attenuation as a function of the length of a signal propagationpath. In the induction-based communication technology, the signal levelis inversely proportional to the third power of the length of the signalpropagation path, whereas in the radio-based technology, the signallevel is inversely proportional to the second power of the length of thesignal propagation path. This results in a dramatic difference in thespatial sensitivity of the communication and means that with theinduction-based technology it is possible to recognize the portableapparatus 100 that wants to pair with the counterpart apparatus 106,whereupon the actual pairing may be performed with the radio-basedtechnology. A typical coverage of the induction-based communication isof the order of human dimensions, i.e. about 1.5 meters.

The induction-based transmitter 102 may be a kilohertz-rangetransmitter, a passive radio-frequency identification tag, or a nearfield communication transmitter, for example. Correspondingly, theinduction-based receiver 108 may be a kilohertz-range receiver, aradio-frequency identification tag reader, or a near field communicationreceiver, for example. The kilohertz-range transmission may operate at5-kilohertz frequency, for example. Higher frequencies, such as thoseexceeding 200 kilohertz, may also be possible. In an embodiment, thekilohertz-range includes 125 kilohertz. Near field communication mayrefer to a short-range high frequency wireless communication technology,known also as NFC, which enables communication over about a10-centimeter distance.

The radio transceiver 104, 110 may be a proprietary transceiver, or aBluetooth-based transceiver, for example. Emerging ultra low powerBluetooth technology may be used, as its expected use cases includeheart rate monitoring. The proprietary radio transmission may be basedon W.I.N.D or ANT technology, for example, both operating at2.4-gigahertz frequency. ANT is a proprietary wireless sensor networktechnology featuring a wireless communications protocol stack thatenables semiconductor radios especially in the sports sector, fitnessand cycling performance monitoring, for example. Another alternative isZigBee, i.e. a suite of high level communication protocols using small,low-power digital radios based on the IEEE 802.15.4-2003 standard forwireless personal area networks.

Next, the communication between the portable apparatus 100 and thecounterpart apparatus 106 is described as a communication sequence112-114-116-118-120-122-124. The communication sequence described inFIG. 1 is in no absolute chronological order. Other functions, notdescribed in this application, may also be executed within the sequence.Some parts of the sequence may also be left out or replaced by acorresponding part.

An identifier, associated with the radio transceiver 104 of the portableapparatus 100, needs to be known by the induction-based transmitter 102of the portable apparatus 100. This may be implemented in any suitableway: the identifier is communicated 112 during the use of the portableapparatus 100 from the wireless transceiver 104 to the induction-basedtransmitter 102, for example. This communication 112 may be implementedwith suitable interface technologies, such as a message interface,method interface, sub-routine call interface, block interface, or anymeans enabling communication between functional sub-units. Anotherpossibility is that the identifier is programmed in a memory of theinduction-based transmitter 102 during manufacture or service of theportable apparatus 100.

The radio transceiver 104 of the portable apparatus 100 may beconfigured to provide 114 its identifier to the radio transceiver 110 ofthe counterpart apparatus 106. However, this is not enough: as wasexplained in the Background section, there may be many portableapparatuses operating simultaneously and transmitting their identifiers,and as result of this, the counterpart apparatus 106 does not know withwhich portable apparatus it should be paired with. Picture the followingscenario in a health club: a user armed with the portable apparatus 100wishes to exercise with the counterpart apparatus 106, but thecounterpart apparatus 106 cannot decide whether it should be paired withthe identifier 114 transmitted by the portable apparatus 100 or withanother identifier 126 transmitted by another portable apparatus.

For that reason, the induction-based transmitter 102 of the portableapparatus 100 is configured to wirelessly provide 118 the identifier tothe counterpart apparatus 106 by a magnetic field, and theinduction-based receiver 108 of the counterpart apparatus 108 isconfigured to wirelessly obtain 118 the identifier from the portableapparatus 100 by the magnetic field.

In an embodiment, the counterpart apparatus 106 may first transmit 116 amagnetic field as a carrier to the portable apparatus 100, whereupon theportable apparatus 100 may modulate this carrier in order to transmit118 the identifier to the counterpart apparatus 106. In that case, theinduction-based receiver 108 of the counterpart apparatus 106 alsocomprises a transmitter (not illustrated in FIG. 1) configured totransmit the carrier. Such an embodiment may resemble reading of apassive RFID tag/transponder, where reading distances may vary from tencentimeters up to a few meters.

As illustrated in FIG. 1, the identifier received by the counterpartapparatus 106 is then provided 120 from the induction-based receiver 108to the radio transceiver 110 of the counterpart apparatus 106. Thiscommunication 120 may be implemented with suitable interfacetechnologies, such as a message interface, method interface, sub-routinecall interface, block interface, or any means enabling communicationbetween functional sub-units.

Now that the counterpart apparatus 106 knows with which portableapparatus 100 it needs to execute the pairing protocol, the next part ofthe sequence may be performed. The radio transceiver 104 of the portableapparatus 100 associated with the identifier is configured to execute122 the pairing protocol utilizing the identifier with the counterpartapparatus 106 by electric radiation, and the radio transceiver 110 ofthe counterpart apparatus 106 is configured to execute 122 the pairingprotocol utilizing the identifier with the portable apparatus 100 byelectric radiation.

Having been paired together, the portable apparatus 100 and thecounterpart apparatus 106 may now proceed to the last part of thesequence. The radio transceiver 104 of the portable apparatus 100 isconfigured to communicate 124 information with the counterpart apparatus106 by electric radiation, and the radio transceiver 110 of thecounterpart apparatus 106 is configured to communicate 124 informationwith the portable apparatus 100 by electric radiation. The informationmay be any data that the portable apparatus 100 and the counterpartapparatus 106 need to communicate to each other. The information may bespecific to a user of the portable apparatus 100, specific to theportable apparatus 100, or specific to the counterpart apparatus 106.The information may be heart activity data, which may include heart rateinformation, beat-to-beat intervals, and/or an electrocardiogram (ECG),for example. Other possible information include heart rate limits,calorie information, body temperature of the user, status of the batteryof the portable apparatus 100, training schedules, equipmentidentification information, user information, registration information,etc.

The identifier associated with the radio transceiver 104 of the portableapparatus 100 may be any identifier used in the pairing protocol. Theterm ‘pairing protocol’ refers here to any protocol that is used in adhoc based communication to recognize the parties of the communication.The identifier may be a medium access control (MAC) address of the radiotransceiver 104, or a part of a medium access control address of theradio transceiver 104. Bluetooth utilizes such MAC addresses, forexample.

Table 1 describes a unique 48-bit Bluetooth device address (LSB=Leastsignificant bit, MSB=Most significant bit). Such an address may beobtained from the IEEE Registration Authority. The device addresscomprises two main fields: a company_id field, and a company_assignedfield. The company_id field comprises two fields: UAP field and NAPfield. The company_assigned field comprises only one field: LAP field.

TABLE 1 Bluetooth device address (BD_ADDR) LSB MSB company_assignedcompany_id LAP UAP NAP 0000 0001 0000 0000 0000 0000 0001 0010 0111 10110011 0101

As was earlier described in connection with the communication sequence,the radio transceiver 104 of the portable apparatus 100 may beconfigured to provide 114 its identifier to the radio transceiver 110 ofthe counterpart apparatus 106. In Bluetooth, this may be performed in aso-called promiscuous mode. This has an effect that the radiotransceiver 110 of the counterpart apparatus 106 knows all identifiersof those portable apparatuses that are within the reception range. Forthat reason, it may be so that only a part of the MAC address needs tobe transmitted 118 as an identifier by the induction-based transmitter102 of the portable apparatus 100. The induction-based transmitter 102may be configured to wirelessly provide 118 a predetermined number ofthe least significant bits of the medium access control address of theradio transceiver 104, and the induction-based receiver 108 may beconfigured to wirelessly receive 118 the predetermined number of theleast significant bits of the medium access control address of the radiotransceiver 104.

Let us take three example addresses, from which only the 16 leastsignificant bits are shown:

-   -   address 1: 01101010 10101011;    -   address 2: 11001101 10101000; and    -   address 3: 11001101 00000000.

The predetermined number of the least significant bits could be 7 bits,for example. The first of these bits may start after the first bit thathas the value one starting from the least significant bit. These bitsare in bold and they are underlined in the example addresses.

FIG. 6 illustrates an embodiment wherein a biosignal measured by theportable apparatus 100 is used as the identifier for the pairingprotocol. The portable apparatus 100 utilizes a biosignal detectioncircuitry 600 to provide a biosignal 602 of the user to theinduction-based transmitter 102 and to the radio transceiver 104. Thebiosignal detection circuitry 600 may be configured to detect abiosignal from the person's skin. The biosignal measured from the usermay be an electrocardiogram, an electromyogram, or some otherbiological/physical parameter measured from the user, or some otherparameter further processed from a parameter measured from the user,such as heart rate, heart beat interval, heart activity data, heart rateaverage over a time period, change pattern of heart rate, or some otherparameter relating to heart action, or muscular action, or some otheraction relating to a physiology of the user.

An example of a biosignal detection circuitry 600 is described in theU.S. Pat. No. 4,625,733 which is incorporated herein by reference.

The induction-based transmitter 102 of the portable apparatus 100transmits reference biosignal data 604 to the counterpart apparatus 106,and the radio transceiver 104 of the portable apparatus 100 transmits acandidate biosignal transmission 606 to the counterpart apparatus 106.The reference biosignal data 604 and the candidate biosignaltransmission 606 may either be the unprocessed biosignal 602 or somefurther processed result of the biosignal 602. Consequently, thereference biosignal data 604 and the candidate biosignal transmission606 may be at least a portion of an electrocardiogram, at least a partof an electromyogram, heart rate, heart beat interval, heart activitydata, heart rate average over a time period, change pattern of heartrate, for example, or some other parameter based on the biosignal 602.It is to be noted that the reference biosignal data 604 and thecandidate biosignal transmission 606 may have the similar contents, i.e.they are in the same form illustrating the same physiological measure,in which case their comparison is a relatively straightforwardoperation. Alternatively, their contents may be different, in which casethere must be a rule with which their contents are transformed in a formfrom which it can be judged whether the reference biosignal data 604 issimilar with the candidate biosignal transmission or not.

As an example, let us suppose that the reference biosignal data 604comprises a heart rate value.

The counterpart apparatus 106 comprises the communication interface unit108 configured to receive reference biosignal data 604, and the wirelessinterface unit 110 configured to receive a plurality of candidatebiosignal transmissions 606, 624, 628 from candidate biosignaltransmitters of various portable apparatuses 100, 620, 626.

The received reference biosignal data 604 is fed 612 from thecommunication interface unit 108 to a comparison unit 614. The candidatebiosignal transmissions 606, 624, 628 are also fed 616 from the wirelessinterface unit 110 to the comparison unit 614.

The comparison unit 614 is configured to compare the reference biosignaldata 612 with the candidate biosignal transmissions 616, thus resultingin comparison data 618.

The wireless interface unit 110 is configured to execute a pairingprotocol 608 with a candidate biosignal transmitter 104 of a candidatebiosignal transmission 606 by utilizing the comparison data 618,whereupon the actual information transmission 610 over radiotransceivers 104, 110 may be started.

In effect, the counterpart apparatus 106 recognizes that the firstportable apparatus 100 is within the range of the communicationinterface unit 108 as the first portable apparatus 100 is the only whosereference biosignal data 604 is received. The reference biosignal data622, 630 transmitted by two other portable apparatuses 620, 626 is notreceived by the counterpart apparatus 106 as the two portableapparatuses 620, 626 are not within the reception range of thecommunication interface unit 108 of the counterpart apparatus 106.

The counterpart apparatus 106 then discards the candidate biosignaltransmissions 624, 628 of the portable apparatuses 620, 626 whosereference biosignal data 622, 630 was not received.

In an embodiment, the candidate biosignal transmission 606 includes anidentifier associated with the candidate biosignal transmitter 104. Thecomparison unit 614 is further configured to input 618 an identifier ascomparison data to the wireless interface unit 110, which identifier isassociated with the candidate biosignal 606 corresponding to thereference biosignal data 604. In this way it is easy to adjust thewireless interface unit 110 to receive the right candidate biosignaltransmission 606, discarding the other transmissions 624, 628.

FIG. 7 illustrates another embodiment relating to the biosignal use inpairing. There are two different biosignal detection circuitrys 600,708, the one 600 is in the portable apparatus 100 detecting thebiosignal 700, and the other 708 in the counterpart apparatus 106.

The biosignal detection circuitry 708 of the counterpart apparatus 106is configured to detect a biosignal from the person's skin and generatethe reference biosignal data 710 from the biosignal. The communicationinterface unit 108 is electrically coupled to the biosignal detectioncircuitry 708. This may be implemented such that the biosignal detectioncircuitry 708 is a part of a hand-grip heart rate monitor coupled to anexercise apparatus. A stepper or an stationary exercise bike, forexample, may include such hand-grip heart rate monitor measuring theheart rate of the user while s/he grips a handlebar including the heartrate measuring sensors.

In the embodiment of FIG. 7, the communication interface unit 108 isreduced merely to an input interface, not even an induction-basedreceiver is needed.

The reference biosignal data 712 and the candidate biosignaltransmissions 714 are compared in the comparison unit 614 in order tofind out the right portable apparatus 100. The comparison unit 614controls 716 the wireless interface unit 110 to execute the pairing 704with the portable apparatus 100 that transmitted the candidate biosignaltransmission 702 corresponding with the reference biosignal data 708,whereupon the information transmission 706 may commence.

In an embodiment, the counterpart apparatus 106 includes both thebiosignal detection circuitry 708 and the communication interface unit108.

Next, FIGS. 2, 3 and 4 illustrate various embodiments of the portableapparatus 100 and the counterpart apparatus 106, wherein the portableapparatus 100 is implemented as a heart rate monitor. Polar Electro®(www.polarusa.com) designs and manufactures heart rate monitors andtheir accessories. At the time of filing this patent application, theapparatus may be implemented based on a Polar WearLink® transmitterW.I.N.D., which is a textile transmitter belt 202 worn around the chestof the user 200 to transmit heart activity data, and on a Polar RS800sdRunning Computer, which is a user interface unit 204 of the heart ratemonitor. The transmission of the heart activity data may utilize theprinciples of time division and/or packet transmission, for example.

The user interface unit 204 may be worn around the wrist, like a watch,but it may well be implemented to another kind of platform, such as asubscriber terminal of a radio system: a mobile telephone for example.The user interface unit 204 may also be a sports watch for use as aninstrument in sports.

FIG. 2 describes an embodiment, wherein the heart rate transmitter 202wearable on the chest of the user 200 comprises both the induction-basedtransmitter (=a kilohertz-range transmitter, for example) 102 and theradio transceiver (=a Bluetooth transceiver, for example) 104. First,the Bluetooth transceiver may transmit 114 its identifier (BD_ADDR, forexample) to the counterpart apparatus 106. Next, the heart ratetransmitter 202 may utilize the kilohertz-range transmitter to transmit118 the identifier of the Bluetooth transceiver (7 bits of the BD_ADDR,as described above, for example) to the counterpart apparatus 106. Thecounterpart apparatus 106 is then able to identify the correct portableapparatus 100. The heart rate transmitter 202 (or to be precise, itsBluetooth transceiver) and the counterpart apparatus 106 may then bepaired 122 with each other, whereupon information communication 124 maystart.

FIG. 3 describes an embodiment, wherein the user interface unit 204comprises both an induction-based transmitter (=a passiveradio-frequency identification tag, for example) 102 and the radiotransceiver (=a Bluetooth transceiver, for example) 104. First, theBluetooth transceiver may transmit 114 its identifier (BD_ADDR, forexample) to the counterpart apparatus 106. Next, the passiveradio-frequency identification tag may provide 118 the identifier of theBluetooth transceiver (BD_ADDR, or a part of it as described above, forexample) to the counterpart apparatus 106. The earlier described carriermechanism 116 may be used here as well. The counterpart apparatus 106 isthen able to identify the correct portable apparatus 100. The userinterface unit 204 (or to be precise, its Bluetooth transceiver) and thecounterpart apparatus 106 may then be paired 122 with each other,whereupon information communication 124 may start.

FIG. 4 describes an embodiment, wherein the heart rate transmitter 202wearable on the chest of the user 200 comprises the induction-basedtransmitter (=a kilohertz-range transmitter, for example) 102, and theuser interface unit 204 comprises the radio transceiver (=a Bluetoothtransceiver, for example) 104.

First, the Bluetooth transceiver may transmit 114 its identifier(BD_ADDR, for example) to the counterpart apparatus 106. Next, the heartrate transmitter 202 may utilize the kilohertz-range transmitter totransmit 118 the identifier of the Bluetooth transceiver (7 bits of theBD_ADDR, as described above, for example) to the counterpart apparatus106.

The identifier may be transmitted as stand-alone information, or encodedwithin a stream of heart activity data. Encoding is described in twoother patents of the applicant: U.S. Pat. Nos. 5,611,346 and 5,632,279.

As was explained earlier, the identifier may be associated with theradio transceiver 104 of the portable apparatus 100. However, otherembodiments are also feasible. In an embodiment, the identifier isassociated with the portable apparatus 100. The identifier may be anyinformation which is transmitter both by the induction-based transmitter102 and the radio transmitter 104. The counterpart apparatus 106 maycompare the identifiers obtained from the radio transceivers with thoseobtained from the induction-based transmitter 102 and establish aconnection or start data transfer with such a radio transceiver thattransmits an identifier matching with an identifier communicated by theinduction-based transmitter 102. In an embodiment, the identifier is anidentifier of the induction-based transmitter 104. The identifier maydefine a transmission channel of the induction-based transmitter 102.The code space defining the possible identifiers of the transmissionchannel of the induction-based transmission may be rather limited. Ifthe same code occurs twice or more frequently in the counterpartapparatus 106, the counterpart apparatus 106 may transmit an enquirymessage to the portable apparatus 100 in order to obtain additionalidentifiers. Such identifiers may be based on heart rate information,such as time interval of successive heart pulses.

The counterpart apparatus 106 is then able to identify the correctportable apparatus 100. The user interface unit 204 (or to be precise,its Bluetooth transceiver) and the counterpart apparatus 106 may then bepaired 122 with each other, whereupon information communication 124 maystart.

It is to be noted that in this embodiment the heart rate transmitter 202may continue to transmit 400 heart activity data.

It is to be noted that when the separate transmitter belt 202 and userinterface unit 204 are used, the processing of the heart activitymeasurements may be distributed between the transmitter belt 202 and theuser interface unit 204. The choice of the distribution depends on theprocessing power and power consumption requirements and on thetransmission capacity, and it may have an effect on how the describedcommunication is best implemented.

FIG. 8 illustrates a further embodiment employing both the transmitterbelt 202 and the user interface unit 204 in the role of the portableapparatus 100. The transmitter belt 202 comprises the biosignaldetection circuitry 600. As can be seen from FIG. 8, the transmitterbelt 202 is of a duo-transmitter type: it comprises both theinduction-based transmitter 102 and the radio transceiver 104. Thebiosignal 800 is fed to both transmitters 102, 104. The induction-basedtransmitter 102 transmits the reference biosignal data 802 to thecounterpart apparatus 106. The radio transceiver 104 transmits thebiosignal 810 to a radio transceiver 814 of the user interface unit 204.The user interface unit 204 may comprise a controller 812 configured tocontrol the radio transceiver 814 to transmit the candidate biosignaltransmission 816 to the counterpart apparatus 106. The counterpartapparatus then operates 804, 806, 808 as described earlier. The pairing818 may be performed between the radio transceiver 814 of the userinterface unit 204, whereupon the actual information transmission 820may begin. In some situations, the actual information transmission maybe from the radio transceiver 104 of transmitter belt 202 directly tothe radio transceiver 110 of the counterpart apparatus 106.

FIG. 9 illustrates an alternative embodiment employing both thetransmitter belt 202 and the user interface unit 204 in the role of theportable apparatus 100. The biosignal detection circuitry 600 inputs 900the biosignal to the radio transceiver 104 of the transmitter belt 202for transmission 902 to the radio transceiver 814 of the user interfaceunit 204. The controller 812 inputs the received biosignal to theinduction-based transmitter 102 of the user interface unit 204. Thereference biosignal data 904 is then transmitted from the user interfaceunit 204 to the counterpart apparatus 106. Also, the candidate biosignaltransmission 906 is transmitted from the user interface unit 204 to thecounterpart apparatus 106. Again, the counterpart apparatus 106 performsthe earlier described appropriate processing 912, 914, 916. Finally,pairing 908 and the information transmission 910 are performed.Alternatively, the actual information transmission may be performed fromthe radio transceiver 104 of transmitter belt 202 directly to the radiotransceiver 110 of the counterpart apparatus 106.

In an embodiment, the heart rate transmitter 202 is integrated into theuser interface unit. In such a case, the biosignal detection circuitry600 may be implemented with a technology which detects the biosignaloptically, electrically or mechanically from the user's tissue.

The implementation of the earlier described embodiments in such anexisting product requires relatively small and well-definedmodifications. Only the above-described communication needs to beimplemented. Naturally, as the products evolve, the feasible platformsfor the implementation of the embodiments described in this patentapplication also evolve and emerge.

Other implementations may also be possible. The heart rate monitor mayalso be implemented so that, instead of the solution comprising thetransmitter belt 202 and the user interface unit 204, the heart rate maydirectly be measured from the wrist on the basis of the pressure, forexample. Other ways for measuring the heart rate may also be employed.As sensor technology becomes more integrated, less expensive, and itspower consumption characteristics are improved, the sensor measuringheart activity data may also be placed in other arrangements besides thetransmitter belt 202. Polar Electro® is already marketing clothes thatmay be provided with separate small sensor units wirelesslycommunicating with the wrist unit 204.

The portable apparatus 100 may be a part of a heart rate monitor formeasuring the user's heart rate and possibly other parameters that canbe measured non-invasively (such as blood pressure). In U.S. Pat. No.4,625,733, which is incorporated herein by reference, Saynajakangasdescribes a wireless and continuous heart rate monitoring concept wherea transmitter to be attached to the user's chest measures the user'sECG-accurate (electrocardiogram) heart rate and transmits the heart rateinformation telemetrically to the heart rate receiver attached to theuser's wrist by using magnetic coils in the transmission.

FIG. 10 illustrates some further embodiments of the counterpartapparatus 106.

In an embodiment, the counterpart apparatus 106 comprises a matchedfilter generator 1002 configured to generate a matched filter from thereference biosignal data 1000. Additionally, the comparison unit 614 isconfigured to apply the matched filter to the candidate biosignaltransmissions 1008 and use the output of the matched filter as thecomparison data 1010.

In another embodiment, the communication interface unit 108 isconfigured to receive reference biosignal data 1000 from a plurality ofreference biosignal transmitters (100, 202 or 204, not illustrated inFIG. 10). Additionally, the communication interface unit 108 comprises awireless proximity detection unit 1004 configured to determine proximityinformation characterizing the proximity of the reference biosignaltransmitters to the apparatus 106. The comparison unit 614 is alsoconfigured to select the reference biosignal data on the basis of theproximity information. This embodiment may be useful in situations wherethe reference biosignal transmitters have a relatively long range, asthe proximity information aids in determining which reference biosignaltransmitter is closest to the counterpart apparatus 106.

In a further embodiment, the wireless interface unit 110 comprises asignal strength estimator 1006 configured to estimate the signalstrength of the candidate biosignal transmissions 1008. Additionally,the comparison unit 614 is configured to compare the reference biosignaldata 1000 with the candidate biosignal transmissions 1008 in orderdetermined by the signal strength. This embodiment may improve theefficiency in finding the right candidate transmission, as it is likelythe one with the highest (or among the highest) signal strength.

Next, a communication method will be described with reference to FIG. 5.The operations described in FIG. 5 are in no absolute chronologicalorder. Other functions, not described in this application, may also beexecuted between the operations or within the operations. Some of theoperations or parts of the operations may also be left out or replacedby a corresponding operation or part of the operation. The method startsin 500. In 502, an identifier of a radio transceiver is wirelesslycommunicated from a portable apparatus to a counterpart apparatus by aninduction-based magnetic field. In 504, a pairing protocol utilizing theidentifier is executed between the radio transceiver of the portableapparatus and a radio transceiver of the counterpart apparatus byelectric radiation. In 506, information is communicated between theradio transceiver of the portable apparatus and the radio transceiver ofthe counterpart apparatus by electric radiation. The method ends in 508.The above-described embodiments of the apparatuses may also be used toenhance the method.

As technology advances, the inventive concept can be implemented invarious ways. The invention and its embodiments are not limited to theexamples described above but may vary within the scope of the claims.

1. An apparatus comprising: a communication interface unit configured toreceive reference biosignal data; a wireless interface unit configuredto receive a plurality of candidate biosignal transmissions fromcandidate biosignal transmitters; and a comparison unit configured tocompare the reference biosignal data with the candidate biosignaltransmissions, thus resulting in comparison data, the wireless interfaceunit being configured to execute a pairing protocol with a candidatebiosignal transmitter of a candidate biosignal transmission by utilizingthe comparison data.
 2. The apparatus of claim 1, wherein thecommunication interface unit applies an induction-based receivercomprising at least one of a kilohertz-range receiver, a radio-frequencyidentification tag reader, a near field communication receiver.
 3. Theapparatus of claim 1, wherein the wireless interface unit comprises aproprietary transceiver, or a Bluetooth-based transceiver, or an ANTtransceiver.
 4. The apparatus of claim 1, wherein the apparatus furthercomprises a biosignal detection circuitry configured to detect abiosignal from the person's skin and generate the reference biosignaldata from the biosignal, and the communication interface unit iselectrically coupled to the biosignal detection circuitry.
 5. Theapparatus of claim 1, wherein the reference biosignal data comprises atleast one of the following: at least a portion of an electrocardiogram,at least a part of an electromyogram, heart rate, heart beat interval,heart activity data, heart rate average over a time period, changepattern of heart rate.
 6. The apparatus of claim 5, wherein the at leastone candidate biosignal data comprises at least one of the following: atleast a portion of an electrocardiogram, at least a part of anelectromyogram, heart rate, heart beat interval, heart activity data,heart rate average over a time period, change pattern of heart rate. 7.The apparatus of claim 1, wherein the candidate biosignal transmissionincludes an identifier associated with a candidate biosignaltransmitter, and the comparison unit is further configured to input anidentifier as comparison data to the wireless interface unit, whichidentifier is associated with the candidate biosignal corresponding tothe reference biosignal data.
 8. The apparatus of claim 1, furthercomprising a matched filter generator configured to generate a matchedfilter from the reference biosignal data, and the comparison unit isfurther configured to apply the matched filter to the candidatebiosignal transmissions and use the output of the matched filter as thecomparison data.
 9. The apparatus of claim 1, wherein the communicationinterface unit is configured to receive reference biosignal data from aplurality of reference biosignal transmitters, and the communicationinterface unit comprises a wireless proximity detection unit configuredto determine proximity information characterizing the proximity of thereference biosignal transmitters to the apparatus, the comparison unitis further configured to select the reference biosignal data on thebasis of the proximity information.
 10. The apparatus of claim 1,wherein the wireless interface unit comprises a signal strengthestimator configured to estimate the signal strength of the candidatebiosignal transmissions, and the comparison unit is further configuredto compare the reference biosignal data with the candidate biosignaltransmissions in order determined by the signal strength.
 11. Theapparatus of claim 1, wherein the apparatus comprises an electroniccircuit, a computer, an exercise apparatus, a health club apparatus, awrist apparatus.